Currently, a wide range of electronic devices adopt touch panels, touch pads, and the like (which are collectively referred to below as touch panels) as input devices. There have been proposed a variety of input devices in which, when an operator operates a touch panel, the touch panel undergoes vibration to thereby provide the operator with an operational feeling on a finger or the like as a feedback. (Refer to Patent Literature 1, for example.)
FIG. 8 is an exploded external perspective view of the electronic device described in Patent Literature 1. As illustrated in FIG. 8, the electronic device (display device) described in Patent Literature 1 includes a display monitor 100, a panel fixing frame 210, a touch panel 400, and a cover 500. The electronic device is configured by assembling the components such as the touch panel 400 to the display monitor 100.
In the electronic device described in Patent Literature 1, the display monitor 100 is configured by using a liquid crystal display (LCD), and the whole display monitor 100 has a rectangular and flat shape. The display monitor 100 is mounted to a circuit substrate that is not illustrated, and in accordance with control by a display control circuit mounted on the circuit substrate, the display monitor 100 displays objects such as a key or a button, or various information on a display surface thereof. Over the display surface of the display monitor 100, the touch panel 400 having substantially the same size as the monitor 100 is disposed.
The touch panel 400 includes, for example, a transparent resin plate and a matrix switch circuit formed on the transparent resin plate. The touch panel 400 is configured to output, in response to a contact made to the panel surface by the finger of the operator or the like, a detection signal corresponding to a position of the contact to a touch panel control circuit mounted on a circuit substrate that is not illustrated. That is to say, by making an operation to the touch panel 400 in accordance with display on the display monitor 100 shown through the touch panel 400, the operator is able to input to the electronic device various information in accordance with the display.
In the electronic device, a piezoelectric element (piezo-element) 420 is adhered along each of two opposing sides on a rear surface of the touch panel 400. When the touch panel 400 detects a contact made by the operator, the electronic device applies a drive signal (voltage) to the piezoelectric elements 420 from a piezoelectric element driving circuit mounted on a circuit substrate that is not illustrated. Consequently, the piezoelectric elements 420 are expanded and contracted, thereby generating a vibration on the operation surface of the touch panel 400. In other words, by the touch panel 400 being vibrated in response to the operation, the operator is able to achieve the operational feeling.
The touch panel 400 is assembled to the display monitor 100 via the panel fixing frame 210. The panel fixing frame 210 is constituted by using a hard resin material such as ABS and accordingly, the entire panel fixing frame 210 has rigidity.
Holders 220, for holding the touch panel 400 at four corners thereof, are assembled to the panel fixing frame 210. FIG. 9 is an enlarged view illustrating that one of the four holders 220 is attached to a corner of the touch panel 400. Each holder 220 is provided with a slit-shaped insert portion 360 into which a corner of the touch panel 400 may be inserted. Furthermore, as illustrated in FIG. 8, each peripheral side surface of the panel fixing frame 210 is provided with fixing holes 320 for fixing a holder 220 near an end portion of the side surface. By inserting hooks 340a provided in the holders 220 as illustrated in FIG. 9 into the fixing holes 320 of FIG. 8, each holder 220 fixes the touch panel 400 to the panel fixing frame 210.
In this way, when the four corners of the touch panel 400 are inserted to the holders 220, each holder 220 holds the touch panel 400 by locking the touch panel 400 from outside at the four corners and from both sides in a thickness direction. As a result, the electronic device described in Patent Literature 1 may be arranged with the touch panel 400 being fixed.
The holders 220 are integrally molded by using a material, such as a silicon-based resin or rubber, having a smaller elastic coefficient than the panel fixing frame 210. Thus, the holders 220 stably hold the touch panel 400 and are also configured to be elastically deformable so as to allow vibration of the touch panel 400. There is also secured a gap between the touch panel 400 and the display monitor 100, for allowing displacement of the touch panel 400 in the thickness direction. As a result, during vibration of the piezoelectric element 420, the touch panel 400 may be displaced in the thickness direction in accordance with the vibration.
Thus, the electronic device described in Patent Literature 1 is configured not to prevent, at the time of vibrating the touch panel 400, the vibration significantly, and therefore, the electronic device is capable of maintaining a good operational feeling provided by the vibration of the touch panel 400.